"A vertical separation of 1,000 feet must be maintained between two aircraft. An International Civil Aviation Organization study showed that wind turbulence of an A-380 can travel up to 300 metres, which is 985 feet. The initial reports we are getting is the SIA aircraft came in the reciprocal wake turbulence caused by another A-380 going in the opposite direction," said a source. The regulator will also check if there was a breach of minimum separation between the two planes, causing more problems for the one at lower level as vortices (air flow from wing tip as a result of producing lift) travel downward. The fact that an A-380 — it is kept airborne by four extremely powerful engines - can shake up another big bird of its size has surprised some. Smaller planes are known to suffer this impact very often — an A-380 caused the same problem to an Indian carrier's aircraft 10 days ago.
The DGCA is now examining these reports about the SIA incident. An aircraft generates two kinds of wake turbulence (simply put, strong wind flows) - one from the engine tip and other is the exhaust from the engine. Both of these shake up air behind and below the aircraft. The regulator will examine which of these wake turbulences could have led to the shake-up on the Mumbai-bound aircraft, if indeed another A-380 was the cause of the turbulence.
Aircraft generate vortices at wing tips because of producing lift. Vortex is stronger in heavier and slow-moving aircraft and is proportional to the wing span of the aircraft. At almost 80 metres, the A-380 has among the widest wing span in commercial aircraft. An SIA statement said 14 crew members and eight passengers were injured on SQ-424. "Of them, eight passengers and 10 crew were hospitalized. Six passengers and all crew were discharged on Sunday from the hospital after thorough medical examination.... SIA will provide full assistance to the authorities in their investigations."